U.S. patent number 7,578,273 [Application Number 11/715,837] was granted by the patent office on 2009-08-25 for device for adjusting the phase angle between two rotating, drive-connected element.
This patent grant is currently assigned to Daimler AG. Invention is credited to Jens Meintschel, Thomas Stolk, Alexander Von-Gaisberg-Helfenberg.
United States Patent |
7,578,273 |
Meintschel , et al. |
August 25, 2009 |
Device for adjusting the phase angle between two rotating,
drive-connected element
Abstract
In a device for adjusting the phase angle between two rotating,
drive-connected elements, which are interconnected by means of an
adjustment device, a control arrangement is provided for the
energy-saving adjustment of the phase angle based on an alternating
torque of one element which is also used in the event of a fault,
to provide for an emergency operation in which the relative angular
phase position between the two elements is kept essentially
constant.
Inventors: |
Meintschel; Jens (Esslingen,
DE), Stolk; Thomas (Kirchheim, DE),
Von-Gaisberg-Helfenberg; Alexander (Beilstein, DE) |
Assignee: |
Daimler AG (Stuttgart,
DE)
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Family
ID: |
35355789 |
Appl.
No.: |
11/715,837 |
Filed: |
March 8, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070199532 A1 |
Aug 30, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/EP2005/009275 |
Aug 27, 2005 |
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Foreign Application Priority Data
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Sep 9, 2004 [DE] |
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10 2004 043 548 |
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Current U.S.
Class: |
123/90.17;
123/90.15; 123/90.31 |
Current CPC
Class: |
F01L
1/3442 (20130101); F01L 1/352 (20130101); F01L
2001/34459 (20130101) |
Current International
Class: |
F01L
1/34 (20060101) |
Field of
Search: |
;123/90.15,90.17,90.31 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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199 14 767 |
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Oct 1999 |
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DE |
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600 13 549 |
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Aug 2001 |
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DE |
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601 02 970 |
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Sep 2001 |
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DE |
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100 38 354 |
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Feb 2002 |
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DE |
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101 27 168 |
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Feb 2002 |
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DE |
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102 20 687 |
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Nov 2003 |
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DE |
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102 24 446 |
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Dec 2003 |
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DE |
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102 57 706 |
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Jan 2004 |
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DE |
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102 48 355 |
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Apr 2004 |
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DE |
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103 32 264 |
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Feb 2005 |
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DE |
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1 128 026 |
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Aug 2001 |
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EP |
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Primary Examiner: Eshete; Zelalem
Attorney, Agent or Firm: Bach; Klaus J.
Parent Case Text
This is a Continuation-In-Part Application of pending International
Patent Application PCT/EP2005/009275 filed Aug. 27, 2005 and
claiming the priority of German Patent Application 10 2004 043
548.0 filed Sep. 9, 2004.
Claims
What is claimed is:
1. A device for adjusting the phase angle between two elements (10,
20) comprising an adjustment device disposed between, and
operatively interconnecting, the two elements (10, 20) for joined
rotation at an adjustable phase angle and means for utilizing an
alternating torque of one element (10) for establishing, in the
event of a fault, a predetermined relative angular phase position
between the two elements (10, 20) suitable for emergency operation,
comprising a free-running mechanism (21) with a locking mechanism
which uses the alternating torque of the one element (10) for
relative angular adjustment between the two elements (10, 20) in
order to reach the emergency running phase position.
2. The device as claimed in claim 1, wherein the free running
mechanism (21) comprises a spring-loaded latch member (22) disposed
on a tooth structure (25, 26) of a corresponding element (24, 32,
33), which tooth structure (25, 26) permits a direction of movement
of the latch member (22) in a first free-running direction (27,
28), but blocks it in the other.
3. The device as claimed in claim 2, wherein the emergency running
position is defined by a tooth gap (29) at which two tooth
structures (25, 26) for opposing free-running directions (27, 28)
of the latch member (22) meet.
4. The device as claimed in claim 2, wherein the free-running
mechanism (21) is arranged in such a way that the alternating
torque acts between a bearing of the latch member (22) and the
corresponding element (24, 32, 33) which supports the tooth
structure (25, 26).
5. The device as claimed in claim 2, wherein means are provided for
lifting the latch member (22) during normal operation off from the
tooth structure (25, 26) in order to release an operative
engagement between the latch member (22) and tooth structure (25,
26).
6. The device as claimed in claim 2, wherein, in a hydraulic
adjustment device (12) with a hydraulic motor including a vane cell
element (17), the tooth structure (25, 26) is arranged on an
impeller wheel (15) which is connected in a rotationally fixed
fashion to the first element (10).
7. The device as claimed in claim 6, wherein the latch member (22)
is connected in a rotationally fixed fashion to the second element
(20).
8. The device as claimed in claim 2, wherein, in a hydraulic
adjustment device (12) including a hydraulic motor with a vane cell
element (17, the tooth structure (25, 26) is connected in a
rotationally fixed fashion to the second element (20).
9. The device as claimed in claim 8, wherein the latch member (22)
is arranged on an impeller wheel (15) which is connected in a
rotationally fixed fashion to the first element (10).
10. The device as claimed in claim 6, wherein the hydraulic motor
is a two-chamber hydraulic motor whose two chambers can be emptied
in the event of a fault.
11. The device as claimed in claim 2, wherein, in an electric
adjustment device (12), the tooth structure (25, 26) is connected
in a rotationally fixed fashion to an actuating shaft (32) of a
gear drive (31), the first element (10) being connected to the
second element (20) by means of the gear drive (31) which has the
actuating shaft (32).
12. The device as claimed in claim 2, wherein, in an electric
adjustment device (12), the tooth structure (25, 26) is connected
in a rotationally fixed fashion to an output (33) of a gear drive
(31), the first element (10) being connected to the second element
(20) by means of the gear drive (31) which has the actuating shaft
(32).
13. The device as claimed in claim 2, wherein, in an electric
adjustment device (12), the tooth structure (25, 26) is arranged in
a gear drive (31), the first element (10) being connected to the
second element (20) by means of the gear drive (31) which has an
actuating shaft (32).
14. The device as claimed in claim 2, wherein during normal
operation the latch member (22) can be lifted off from the tooth
structure (25, 26) by magnetic force.
15. The device as claimed in claim 11, wherein the electric
adjustment device (12) comprises an electric motor as rotational
actuator (30).
16. The device as claimed in claim 11, wherein the electric
adjustment device (12) comprises a hysteresis brake as a rotational
actuator (30).
Description
BACKGROUND OF THE INVENTION
The invention relates to a device for adjusting the phase angle
between two rotating, drive-connected elements with an adjustment
device arranged between the two rotating elements.
Devices of this type are known, for example, in internal combustion
engines and are provided there for the relative adjustment of the
phase angle of the camshaft and a crankshaft which drives the
camshaft. This engagement in the valve drive kinematics influences
the phase angle of the valve opening, the opening period and the
valve stroke in a variable fashion within limits.
Known hydraulic camshaft actuators for adjusting a phase angle of a
camshaft, which activates the valves of an internal combustion
engine, comprise essentially a hydraulic motor which is fed by the
motor oil circuit, operating for example according to the vane cell
principle. Electric camshaft actuators composed of a summing gear
mechanism and rotational actuator have recently become known in
which an electric motor or an electric brake serves as the
rotational actuator. All the systems have to place the phase angle
of the camshaft in a defined emergency running position if faults
occur in the electronics, that is if electric cables, or sensor
systems or the actuator systems fail, or if the electric motor, the
brake and the like become inoperative to ensure that the internal
combustion engine remains operative although with restrictions. In
hydraulic camshaft actuators with their typically small actuating
ranges, this emergency running position is generally located at an
end stop of the camshaft actuator. As a result of the average
camshaft torque, these camshaft actuators generally move without an
oil supply to the late stop, which may be, for example, the
emergency operating position for an inlet valve of the internal
combustion engine. If the "early" stop is the emergency operating
position which is to be set, a restoring spring usually disposed
between the chain wheel and camshaft comes into use. To avoid
noise, the camshaft actuator is generally locked in the emergency
running position.
In order to ensure the operation of internal combustion engines
with camshaft actuators with an extended actuating range in the
event of an emergency, an emergency operating position between the
stops should expediently be provided. This may be done, for
example, by means of two rotational springs, one operating counter
to the other, between the chain wheel and camshaft whose effect is
canceled out in the emergency operating position. However, during
normal operation the camshaft actuator must operate continuously
counter to these springs with the result that its power drain in
terms of pressurized motor oil or electric current is in some cases
considerably increased.
German laid-open patent application DE 102 20 687 discloses a
device for adjusting the angle between two rotating,
drive-connected elements in which, in the event of a failure of the
adjustment device and/or its controller, an emergency position can
be reached and held by braking and locking the adjustment shaft and
by rotating the drive shaft with a suitable transmission ratio.
It is the principle object of the invention to provide a low power
consumption device for adjusting the angle between two rotating,
drive-connected elements which permits an emergency running
position to be reliably adopted and held.
SUMMARY OF THE INVENTION
In a device for adjusting the phase angle between two rotating,
drive-connected elements, which are interconnected by means of an
adjustment device, means are provided for the energy-saving
adjustment of the phase angle based on an alternating torque of one
element which is also used in the event of a fault, to provide for
an emergency operation in which the relative angular phase position
between the two elements is kept essentially constant.
To this end, a non-uniform torque profile on the adjustment device
which is caused, for example, by valve actuation by a camshaft can
be utilized. Herein, a braking effect is generated when the valves
are the actuation cams. During closing, the valves generate a force
effective on the rear cam areas resulting in a forward rotating
force or torque effective on the camshaft.
For the purpose of adjustment in the event of a fault, a
free-wheeling-like mechanism with a one-sided locking means which
acts as a function of the camshaft angle is preferably provided.
The mechanism makes it possible to use the alternating torque of an
element for relative angular adjustment between the two elements in
order to assume an emergency operative position. The
free-running-like mechanism is preferably embodied as a latch
mechanism in such a way that a spring-loaded latch can be moved on
a tooth structure of a corresponding element, which tooth structure
permits the latch to move in a first free-running direction. In
this way the latch can be moved in a defined direction. The latch
is pressed onto the tooth structure by a spring. If a sufficiently
large alternating torque acts between a bearing of the latch and
the corresponding element which supports the tooth structure, the
latch can slide on a flat tooth edge of the tooth structure and
jump into a following tooth gap. A movement in a direction counter
to the free-running direction can be excluded by a correspondingly
steep tooth edge. The process continues until a tooth gap with
steep tooth edges on both sides is reached. If the emergency
operating position to be adopted is located between end stops of
the adjustment device, tooth structures which each act in opposite
directions can expediently be obtained on each side of the
emergency operating position. The emergency operating position can
then be reached very quickly since, for example, in the case of a
four cylinder internal combustion engine components of the
alternating torque which also rotate four times and brake four
times within one revolution of the camshaft also occur, and the
preferred latch mechanism is able to move on by four teeth in the
process.
The emergency running position is preferably arranged in a tooth
gap at which two tooth structures with opposing free-running
directions of the latch meet. The emergency running position can
thus be reliably reached and the latch secured in the tooth gap
until, in order to initiate actuating processes, an operative
connection between the latch and tooth structure the latch will be
moved out of the tooth structure.
The free-running-like mechanism is advantageously arranged in such
a way that the alternating torque acts between a bearing of the
latch and the corresponding element which supports the tooth
structure.
In one preferred embodiment the tooth structure is arranged in a
hydraulic adjustment device with a hydraulic motor including a vane
cell element, on an impeller wheel which is connected in a
rotationally fixed fashion to the first element. The latch is
preferably connected in a rotationally fixed fashion to the second
element, with the latch being preferably radially movable. The
preferred latch mechanism is compact and does not require any
additional installation space. The latch mechanism can be combined
with existing components.
In one favorable embodiment, the tooth structure of a hydraulic
adjustment device with a hydraulic motor with a vane cell element
is connected in a rotationally fixed fashion to the second element.
The latch is preferably arranged on an impeller wheel which is
connected in a rotationally fixed fashion to the first element,
with the latch being preferably axially movable. The preferred
latch mechanism is compact and does not require any additional
installation space.
In a hydraulic adjustment device, a modified hydraulic valve whose
chambers can be emptied in the event of a fault is expediently
provided. It is then impossible for residual oil which may be
present in the vane cells to prevent the emergency running position
from being adopted.
In another favorable embodiment in an electric adjustment device,
the tooth structure is connected in a rotationally fixed fashion to
an actuating shaft of a gear drive, the first element being
connected to the second element by means of the gear drive which
has the actuating shaft. The electric adjustment device comprises
an electric rotational actuator and a gearbox. The gear drive is
preferably embodied as a summing gear mechanism with three shafts,
two inputs and one output. If two of the three shafts are connected
to one another in a rotationally fixed fashion, the gear drive is
locked and the phase angle remains constant.
In a further favorable embodiment, the tooth structure in an
electric adjustment device is connected in a rotationally fixed
fashion to an output of a gear drive, the first element being
connected to the second element by means of the gear drive which
has the actuating shaft.
In a further favorable embodiment in an electric adjustment device,
the tooth structure is arranged in a gear drive, the first element
being connected to the second element by means of the gear drive
which has an actuating shaft.
In an electric adjustment device, it is particularly favorable if
during normal operation the latch can be lifted off from the tooth
structure by magnetic force so that an adjustment process can be
initiated.
If the electric adjustment device is embodied as an electric motor,
a separate electric magnet can be provided for lifting off the
latch from the tooth structure, the coil of which can be connected
electrically in series or in parallel with the adjustment
device.
If the electric adjustment device is embodied as a hysteresis
brake, the latch can be arranged with a favorably small degree of
structural expenditure in such a way that it can be lifted off from
the tooth structure by the magnetic flux of the hysteresis
brake.
The invention will be explained in more detail below on the basis
of exemplary embodiments described with reference to accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a and 1b show a preferred latching mechanism with a tooth
structure which is illustrated in a developed view in an emergency
operating position (1a) and during movement in the direction of the
emergency operating position (b),
FIG. 2 shows a profile of an alternating torque of a camshaft
plotted against a crankshaft,
FIG. 3 is an exploded illustration of a hydraulic camshaft actuator
based on a vane cell principle with a latch mechanism with a
radially movable latch member,
FIG. 4 is an exploded illustration of a hydraulic camshaft actuator
based on the vane cell principle with a latch mechanism with an
axially movable latch member,
FIGS. 5a, 5b, and 5c show, in parts a, b, c, a schematically a
latch mechanism between the actuating input and input (a), a latch
mechanism between the input and output (b), a latch mechanism
between the actuating input and output (c) in an electric camshaft
actuator, and
FIG. 6 is a schematic view of a latch mechanism between the
actuating input and input in an electric camshaft actuator with a
hysteresis brake.
DESCRIPTION OF PARTICULAR EMBODIMENTS
The invention is particularly suitable for a camshaft actuator with
which a phase angle of the camshaft can be varied compared to a
drive, for example a chain wheel, which can be driven by a
crankshaft of an internal combustion engine.
In the figures, identical or substantially identically acting
elements are provided with the same reference symbols.
As is illustrated in FIGS. 1a, and 1b, a preferred
free-running-like mechanism which is embodied as a latch mechanism
21 comprises a latch member 22 in a guide 24, the latch member 22
being pressed by a spring 23 onto a tooth structure 25, 26 which is
illustrated in a developed view. The latch member 22 is arranged in
a tooth gap 29 in an emergency operating position in FIG. 1a, and
in FIG. 1b a movement of the latch member 22 in the direction of
the emergency running position is illustrated. The tooth structure
25 or 26 has flat tooth side edges the teeth rising gradually in
the free-running direction 27 or 28 of the tooth structure 25 or
26, while the trailing edges are arranged in a significantly
steeper, preferably perpendicular fashion. The latch member 22 can
slide over the tooth structure 25 in the free-running direction 27,
or over the tooth structure 26 in the free-running direction 28. In
FIG. 1b, it can be seen how the latch member 22 slides over a tooth
from a tooth gap in the free-running direction 27 and drops into
the next tooth gap. If the latch member 22 reaches the tooth gap
29, it has reached the emergency running position. The tooth
structures 25, 26 which have opposed free-running directions 27, 28
bound the tooth gap 29 on both sides. The tooth gap 29 is bounded
on both sides by steep tooth edges in such a way that the latch
member 22 cannot slide out of the tooth gap 29 counter to the
spring pressure of the spring 24. In order to interrupt an
operative connection between the latch member 22 and the tooth
structures 25, 26 during normal operation and to initiate an
adjustment process, the latch member 22 must be lifted off from the
tooth structure 25, 26.
The movement of the latch member 22 in the free-running direction
27 or 28 is made possible by an alternating torque which acts
between a bearing of the latch member 22 and a corresponding
element which supports the tooth structure 25, 26. The profile of
the alternating torque of a camshaft plotted against a crank angle
is outlined in FIG. 2. The torque profile which is recognizably
non-uniform can be felt on an adjustment device of the camshaft.
The peaks in the positive direction correspond to braking
components B which arise as a result of valve activation cams of
the camshaft when said valves open. When the valves close, they
apply a force to the rear side edge of the cams, which forces give
rise to then negative peaks, corresponding to simultaneously
rotating components A. The average camshaft torque M is added to
the image as a dashed constant line. The simultaneously rotating
components A of the alternating torque can advantageously be used
to drive the latch mechanism 21 in the event of a fault.
FIG. 3 shows, in an exploded illustration, a preferred hydraulic
camshaft actuator with a hydraulic motor based on the vane cell
principle as an adjustment device 12 for adjusting the angle
between two rotating, drive-connected elements 10, 20 which are
interconnected by means of the adjustment device 12, with a latch
mechanism 21 including a latch member 22. The adjustment device 12
comprises an impeller wheel 15 and an outer part 16, the vane cell
element 17, which is in contact with an inner circumference of the
second element 20 which is embodied as a chain wheel. The second
element 20 can also be embodied as a pulley. The impeller wheel 15
is provided with a tooth structure 25, 26, as described in FIG. 1,
and is connected in a rotationally fixed fashion to the first
element 10 which is embodied as a camshaft. The spring-loaded latch
member 22 of the preferred latch mechanism 21 is radially movable
and in the event of a fault engages in the tooth structure 25, 26.
The latch member 22 which moves radially inwards as a result of its
spring 23 is connected in a rotationally fixed fashion to the outer
part 16 of the second element 20 which is embodied as a chain
wheel. The adjustment device 12, which is embodied as a hydraulic
motor, is covered with a first cover plate 13 and a camshaft-end
cover plate 14.
During normal operation, the latch member 22 is pressed by the oil
pressure prevailing in the vane cells 12 in the direction of the
spring 23 so that the latch member 22 is lifted off from the tooth
structure 25, 26 and no contact occurs. If the adjustment device 12
which is embodied as a hydraulic motor fails, the oil pressure in
the vane cells 17 also collapses. The latch member 22 then is
biased toward the tooth structure 25, 26 under the effect of the
spring 23, and the emergency running position is established as a
result of the alternating torque. Since residual oil in the vane
cells 17 can impede this process, it is advantageous if the vane
cells 17 are emptied in an emergency operation. This can be done,
for example, by means of a modified multi-path hydraulic valve
which in addition to customary positions--filling direction
1/emptying direction 2, and filling direction 2/emptying direction
1 and holding--has a de-energized position in which both chambers
are emptied.
An alternative embodiment with an axially movable latch member 22
is shown by FIG. 4. The design corresponds largely to the design in
FIG. 3. For elements which are not explained in more detail here,
reference is made to the description of FIG. 3. The latch member 22
is mounted in the impeller wheel 15 and acts on the second cover
plate 14 in which the tooth structure 25, 26 is formed. The cover
plate 14 is connected in a rotationally fixed fashion to the second
element 20 which is embodied as a chain wheel. During normal
operation, as described above, the latch member 22 is lifted off
from the tooth structure 25, 26 by the oil pressure prevailing in
the vane cells 17, and in the event of a fault when the oil
pressure is absent it engages in the tooth structure 25, 26 and
provides for the emergency running operation.
FIGS. 5a, 5b, 5c and 6 illustrate a plurality of preferred
embodiments which have an electric adjustment device 12. The
adjustment device 12 comprises an electric rotational actuator 30
and a gear drive 31. The rotational actuator 30 can be embodied as
an electric motor or as a passive brake in the form of a hysteresis
brake. The adjustment device 12 activates an actuating input 32
which acts on the gear drive 31 which is in particular a summing
gear mechanism. The first element 10 is located at the output of
the gear drive 31. The input of the gear drive 31 is formed by the
second element 20, embodied as a drive. The drive can be embodied
as a chain wheel or as a pulley. If two of the three inputs or
outputs are connected to one another in a rotationally fixed
fashion, the gear drive 31 is locked and the phase angle remains
constant. A device for retracting a latch member 22 of a preferred
latch mechanism 21, such as is described in FIG. 1, during normal
operation is not illustrated. This can be done, for example, by
means of an electric motor whose coil is connected electrically in
series or in parallel with the electric adjustment device 12.
FIGS. 5a, 5b, 5c describe various arrangements of a preferred latch
mechanism 21. In a first preferred arrangement, the latch mechanism
21 is arranged between the actuating input 32 of the gear drive 31
and the input of the gear drive 31 which is formed by the second
element 20, the latch member 22 being connected by its guide 24 in
a rotationally fixed fashion to the input, and the tooth structure
25, 26 being arranged on the actuating shaft (FIG. 5a).
Alternatively, the latch mechanism 21 can be arranged between the
aforesaid input of the gear drive 31 and the output of the gear
drive 31 (FIG. 5b). In this context, the tooth structure 25, 26 is
connected in a rotationally fixed fashion to the first element 10
which is embodied as a camshaft, and the latch is connected by its
guide 24 to the gear drive housing which is connected in a
rotationally fixed fashion to the second element 20. Alternatively,
the latch mechanism 21 can also be arranged within the gear drive
31 between the actuating input 32 and the output of the gear drive
31, the latch being connected by its guide 24 in a rotationally
fixed fashion to the output.
FIG. 6 is a schematic view in an electric camshaft actuator with a
latch mechanism 21 between the actuating input 32 and output of a
gear drive 31 as described in FIG. 5, the rotational actuator 30 of
the electric adjustment device 12 being embodied as a hysteresis
brake. A coil 36 is arranged in a stator 34. If said coil 36 is
energized, a hysteresis ring 33, which engages in a pole structure
35 which is itself embodied on both sides of a gap of the stator
34, is continuously re-magnetized, which brakes the hysteresis ring
33. Since the hysteresis ring 33 is connected by its carrier in a
rotationally fixed fashion to the actuating input 32, the latter is
likewise braked. The actuating input 32 supports the tooth
structure 25, 26 while the latch is connected by its carrier 24 in
a rotationally fixed fashion to the gear drive housing or the
second element 20.
During the energization, the latch member 22 is forced out by the
magnetic flux in the stator 34. The latch member 22 is therefore
expediently formed from a soft magnetic or magnetizable material.
If the stator 34 or its coil 36 is not energized, the spring 23 of
the latch mechanism 21 presses the latch member 22 onto the tooth
structure 25, 26.
* * * * *